Ski boots are specialized footwear that attaches a skier to skis via bindings. While skiing, the boot/binding synergy enables a skier to navigate and transmit control inputs within and to the snow. Originally, ski boots were similar to shoes or boots and manufactured of leather. As technology continues to advance and skiing becomes more specialized, ski and ski boot technology also advances.
Generally, boots intended for downhill use (e.g., Alpine) employ a hard plastic shell with a softer foam liner that provides warmth and comfort. Skiers will appreciate that a thick soft liner will be more comfortable and provide more insulation while thinner, harder liners usually provide more precision and overall control. While comfort continues to improve through the use of conformable linings which allow an otherwise stiff liner to be molded to the foot and comfortably accept a large variety of foot shapes, not much advancement of form fitting an outer shell has been made.
In order to accommodate intended use, comfort and performance goals, shells come in various degrees of stiffness. Beginners typically like a softer and more padded boot that provides warmth and comfort, while more advanced and competitive skiers generally prefer a stiffer boot with a thinner liner which provides them with more precision and control.
By design, most often, softer boots are lighter due to thinner shell material. By contrast, increased boot stiffness generally translates into more precise energy transmission from the skier to the ski. Thus, more aggressive and competitive skiers usually tend to favor a more rigid boot. Unfortunately, stiff boots are often less comfortable and heavier than their softer counterparts.